Diabetic neuropathy is one of the most common chronic complications of diabetes mellitus. It results from nerve damage associated primarily with prolonged exposure to elevated blood glucose levels, together with other metabolic and vascular factors.
It can affect different parts of the nervous system and cause symptoms such as numbness, tingling, burning pain, reduced sensation, and muscle weakness, particularly in the lower limbs.
The most common form is diabetic peripheral polyneuropathy, which usually begins in the feet and toes and may gradually progress upward. In more advanced cases, the hands may also become affected.
Early recognition of diabetic neuropathy is important both for managing symptoms and for preventing complications such as foot ulcers and diabetic foot.
Symptoms of Diabetic Neuropathy
The symptoms of diabetic neuropathy vary depending on the type of neuropathy and the nerves affected.
Diabetic peripheral neuropathy may cause:
- numbness or reduced sensation in the feet
- tingling or a “pins and needles” sensation
- burning or shooting pain
- electric shock-like sensations in the limbs
- increased sensitivity even to light touch
- reduced ability to perceive pain or temperature
- muscle weakness
- muscle cramps
- balance or walking difficulties in more advanced cases
Symptoms usually occur symmetrically and begin in the most distal parts of the lower limbs. As the neuropathy progresses, the characteristic “stocking-glove” distribution may develop.
In some patients, pain is more severe at night and can significantly interfere with sleep and quality of life.
Neuropathic Pain in Diabetes
Painful diabetic neuropathy can cause chronic neuropathic pain, which differs from typical musculoskeletal pain.
It may be described as:
- burning
- electric shock-like sensations
- tingling or pins and needles
- shooting or stabbing pain
- excessive sensitivity to touch
In some patients, even contact between the feet and bedsheets can cause significant discomfort or pain.
Other patients may have substantial nerve damage without severe pain. Loss of protective sensation is particularly important because minor injuries or burns to the feet may go unnoticed.
Diabetic Autonomic Neuropathy
Diabetes can also affect the autonomic nervous system, which regulates many bodily functions that occur without conscious control.
Depending on the nerves affected, diabetic autonomic neuropathy may cause:
- resting tachycardia
- orthostatic hypotension and dizziness when standing
- abnormalities in sweating
- gastroparesis, nausea, or vomiting
- constipation or diarrhea
- bladder dysfunction
- erectile dysfunction
- other forms of sexual dysfunction
These symptoms require appropriate evaluation, as other medical conditions can cause similar problems.
Causes and Risk Factors for Diabetic Neuropathy
The development of diabetic neuropathy is multifactorial. Prolonged hyperglycemia can cause metabolic and vascular changes that gradually impair peripheral nerve function.
The risk increases particularly with a longer duration of diabetes and inadequate glycemic control.
Other factors that may be associated with an increased risk include:
- arterial hypertension
- dyslipidemia
- smoking
- obesity
- increasing age
- cardiovascular risk factors
- chronic kidney disease
Systematic management of modifiable risk factors is an important part of the overall treatment strategy.
Diagnosis of Diabetic Neuropathy
The diagnosis of diabetic neuropathy is based on the patient’s medical history, symptoms, and a detailed neurological examination.
The neurological assessment may include evaluation of:
- sensation to touch and pain
- temperature sensation
- vibration perception
- proprioception
- tendon reflexes
- muscle strength
- balance and gait
Examination of the lower limbs and feet is also particularly important to identify loss of sensation, injuries, or ulcers.
Electromyography and Nerve Conduction Studies
In selected cases, Electromyography and Nerve Conduction Studies (EMG/NCS) may be performed.
These tests can help assess peripheral nerve function, characterize the type of polyneuropathy, and differentiate diabetic neuropathy from other neurological disorders.
They are not necessary for every patient with typical diabetic peripheral neuropathy. They may be particularly useful when the clinical presentation is atypical, significant muscle weakness is present, or another cause of the symptoms needs to be excluded.
Excluding Other Causes of Peripheral Neuropathy
The presence of diabetes does not necessarily mean that every peripheral neuropathy is caused by diabetes.
Depending on the clinical presentation, laboratory or other investigations may be required to exclude alternative causes, such as:
- vitamin B12 deficiency
- thyroid disorders
- kidney or liver disease
- excessive alcohol consumption
- certain medications
- paraproteinemias
- autoimmune or other neurological disorders
Differential diagnosis is particularly important when symptoms progress rapidly, are asymmetrical, or do not follow the typical pattern of diabetic polyneuropathy.
Treatment of Diabetic Neuropathy
The treatment of diabetic neuropathy aims to slow the progression of nerve damage, manage neuropathic pain, maintain function, and prevent complications.
An important part of management is appropriate control of diabetes, according to the individualized treatment goals of each patient.
Management of other risk factors is also important, including:
- arterial hypertension
- dyslipidemia
- smoking
- excess body weight
- physical inactivity
When painful diabetic neuropathy is present, specific classes of medications may be used to manage neuropathic pain. Treatment is individualized according to the severity of symptoms, coexisting medical conditions, potential adverse effects, and the patient’s other medications.
For patients with muscle weakness, balance problems, or mobility limitations, physiotherapy and appropriate exercise may also be beneficial.
Diabetic Foot and Diabetic Neuropathy
Diabetic neuropathy is an important risk factor for the development of diabetic foot complications.
When sensation is reduced, a patient may not notice a minor injury, blister, pressure from footwear, or even a burn. If impaired circulation or infection is also present, a small injury may progress to a more serious ulcer.
Important preventive measures include:
- daily inspection of the feet
- appropriate hygiene and skin care
- wearing suitable footwear
- avoiding walking barefoot
- early treatment of wounds, ulcers, or infections
- regular foot assessment in patients at increased risk
A foot ulcer, changes in skin color or temperature, swelling, discharge, or other signs of possible infection require prompt medical evaluation.
Neurological Follow-Up of Diabetic Neuropathy
Regular neurological follow-up is important for assessing the progression of neuropathy, sensation, muscle strength, and response to treatment.
Particular attention is required when there is rapid progression of symptoms, significant or asymmetrical muscle weakness, severe gait impairment, or symptoms that are not typical of conventional diabetic polyneuropathy, as further investigation for another or additional neurological disorder may be necessary.
Early diagnosis of diabetic neuropathy, appropriate management of diabetes and cardiovascular risk factors, treatment of neuropathic pain, and proper foot care can help reduce complications and contribute to maintaining mobility, daily functioning, and quality of life.